As is well known, in core blowing machines, the supply of a strong stream of air under pressure causes sand and its corresponding additives, to be dragged from a cartridge containing the sand to the inside of a core box which has previously been positioned under a blowing plate provided with apertures suited to the core to be manufactured in order that the sand distribution reaches all the hollows, thereby conforming a perfect core.
In the light of the foregoing, it is clear that different types of cores will require a specific type of blowing plate, and therefore the plates must be removably assembled on the blowing machine, at the same time as throughout the operative stage of a specific blowing plate, sand residues which must be removed regularly are deposited thereon at each phase.
In order to attain this double objective there are known core blowing machines provided with a platform capable of receiving and fixing the blowing plates and which may swing, from a horizontal and working position, to a vertical position for the sand residues to be eliminated, by scraping the plate or by any other means.
In this respect reference should be made to U.S. Pat. No. 4,572,273 which describes a device provided with a swinging platform, the swinging movement whereof is provided by a pair of hydraulic cylinders. The platform is together with the cited hydraulic cylinders, connected to a travelling carriage, which may be displaced through vertical guides on a fixed support and with the collaboration of another hydraulic cylinder, so that this last hydraulic cylinder affords vertical displacement of the platform and consequently of the blowing plate and the core box with respect to the top blowing head, inherent in the normal operation of the core blowing machine, whereas the first pair of cylinders afford the swinging movement of the platform so that the blowing plate may be cleaned.
This device is moreover provided with a fourth hydraulic cylinder, positioned transversally, with which the blowing plate is attached or released with respect to the swinging platform.
This solution, albeit affording attainment of the objectives sought from an operative point of view, is extremely complex from a structural point of view and consequently expensive both as regards manufacture and subsequent maintenance thereof.